The present disclosure relates to an optical information recording medium and a manufacturing method thereof and an optical information recording medium recording layer. In detail, the present disclosure relates to an optical information recording medium with two or more recording layers.
The market for optical information recording media has hitherto been led by CDs (Compact Discs), DVDs (Digital Versatile Discs), and the like. However, in recent years, along with the proliferation of high definition television and a dramatic increase in data handled by PCs (Personal Computers), there is a demand for further increases in the capacities of optical information recording media. To meet such demand, mass storage optical information recording media that are compatible with blue lasers such as BDs (Blu-ray Discs (registered trademark)) have appeared, and markets for new mass storage information recording media are being established.
Although there are rewritable optical information recording media typified by the CD-RW (Compact Disc-ReWritable) and the DVD±RW (Digital Versatile Disc±ReWritable) and write-once type optical information recording media typified by the CD-R (Compact Disc-Recordable) and the DVD-R (Digital Versatile Disc-Recordable) as recordable optical information recording media, the latter in particular have contributed greatly to the expansion of the market as low cost media. Accordingly, with mass storage optical information recording media that are compatible with blue lasers, lowering the cost of write-once type optical information recording media is likewise considered important in order to expand the market. Furthermore, it is generally said that compared to hard disk drives (HDD) or flash memories, optical information recording media have high storage reliability due to the recording and reproduction principle thereof, and are in demand for use as archival media, starting to be used for the storage of critical information.
As the recording material that is used in a write-once type optical information recording medium, there are inorganic materials and organic pigment materials. Although organic pigment materials have mainly been considered for the recording material of a write-once type optical information recording media of the related art, with the mass-storage optical information recording media of recent years, inorganic materials are also being widely considered for the recording material.
For example, an inorganic recording layer that includes In oxide and Pd oxide where the Pd oxide includes Pd monoxide and Pd dioxide and the ratio of Pd atoms with respect to the total of In atoms and Pd atoms is 6 atomic % to 60 atomic % is proposed in Japanese Unexamined Patent Application Publication No. 2010-137545. Further, an inorganic recording layer that includes one or both of In and Sn, Pd, and O is proposed in Japanese Unexamined Patent Application Publication No. 2010-218636.
Incidentally, in recent years, in order to further increase the recording capacity in recordable high-density optical information recording media such as DVDs and BDs, techniques for increasing the number of recording layers have been widely adopted. With a multi-layer optical information recording medium, recording and reproduction of information signals with respect to the recording layer positioned at the deepest position from the information reading face side is performed using laser light that has transmitted through the recording layer to the front side of the recording layer positioned at the deepest position. Therefore, the more recording layers there are, the more recording layers there are through which the laser light transmits before reaching the recording layer positioned at the deepest position, and it is desirable for recording layers other than the recording layer positioned at the deepest position from the information reading face side to have high transmittance.
Demand for further increasing the recording capacity by increasing the number of recording layers is also growing for write-once type optical information recording media, and the improvement of transmittance of inorganic recording layers is an important technique in meeting such a demand.